The invention discloses a method for extracting industrial hemp oil rich in cannabidiol. The method includes the steps that supercritical carbon dioxide fluid is adopted for extracting industrial hemp oil from industrial hemp, during extraction, cooled industrial hemp powder is placed in a material barrel of an extraction kettle, CO2 gas is injected into the extraction kettle, the temperature and pressure in the extraction kettle are kept, the CO2 gas makes contact with raw materials in a supercritical state, the industrial hemp oil and other ingredients in the industrial hemp powder are dissolved in the supercritical fluid, the fluid containing cannabidiol and other ingredients throttles and expands in the extraction kettle and enters a separation kettle to be analyzed, and the industrial hemp oil is obtained and collected. The CO2 fluid in the supercritical state is used as an extraction solvent, reuse is achieved in the same system, the process is simple, energy consumption is low, the extraction period is short, is only 1-2 h and is 1/4 of the production period in the prior art, and the extracted industrial hemp oil has the advantages of being good in quality, high in purity, free of abnormal smells, solvent residues and environmental pollution and the like.